An electron beam emitter commonly includes an electron gun or generator for generating electrons, which is positioned within a vacuum chamber. The vacuum chamber has an electron beam exit window foil at one end through which the electrons from the electron gun are accelerated by a voltage potential imposed between the electron gun and the exit window foil. The electron gun can include a housing enclosing one or more elongate line source filaments, for example two, which produce electrons when electrical power is passed through the filaments. The electron gun housing generally includes a grid pattern of small round holes below the filaments which allow the electrons produced by the filaments to exit the electron gun housing for acceleration out the exit window foil. Typically, the electrons that reach the exit window foil from each filament are focused in a line pattern resembling or corresponding to the narrow elongate shape of the filaments. For example, this can be seen in the graph of FIG. 1, which depicts a typical pattern of electrons at the exit window foil from an electron gun having two elongate filaments, where the electrons are concentrated in two narrow elongate lines 8 corresponding to the two filaments, while the surrounding areas 9 have lower concentrations of electrons. Having a nonuniform electron distribution with such higher and lower intensity electron spots or regions can limit the overall beam power used. In addition, in cases where the electron beam emitter is operated close to a product that is being irradiated or within a low pressure or vacuum environment, with little or no air present to scatter the electrons, the electrons reaching the product could in some situations still be in the pattern depicted in FIG. 1, resulting in uneven irradiation.